This invention relates to the processing of sequences, particularly partial lines of an image, such as X-ray images, and, more particularly, to a technique for converting half-lines of image pixel data to full-lines for subsequent processing and display.
Images generated by X-ray and other imaging systems are acquired in a variety of manners, depending upon the structure and configuration of the detecting subsystems. In general, a detector is employed for receiving image information divided into a matrix of pixels, which, together, define an overall image of interest. The matrix of pixels is commonly divided into rows which are scanned and analyzed sequentially or in a pre-established sequential pattern. The rows of pixels are then reassembled by processing circuitry to reconstitute the useful image, which may be displayed or printed for use by an attending physician or technician.
Various scanning formats and matrix sizes are commonly employed in X-ray and other image processing modalities. In a number of these techniques, the overall image is not only divided into rows of pixels, but each row is further subdivided into half-lines of pixels. For efficient processing of the image data, the half-lines of pixels may be detected and processed in various orders. For example, in a given matrix of image pixels, half-lines of pixel data may be acquired and processed beginning at upper and lower outer edges of the image and proceeding toward a center line of the image parallel to the half-lines of pixels. In other processing techniques, half-lines of pixel data may be processed from a center line of the overall image matrix, proceeding towards upper and lower edges. Moreover, half-lines of pixel data may also be acquired and processed progressively in sequential half-lines beginning at an upper corner of the image and continuing to an opposite lower corner.
Depending upon the pixel data acquisition sequence utilized, pixel data processed by the imaging system may arrive to signal processing circuitry in interlaced half-lines of data which must be sorted to produce a meaningful image. In particular, where alternating half-lines of data arrive from opposite upper and lower portions of an image, the half-lines of data must be sorted and grouped into adjacent full-lines proceeding from one side of the image to the other. In addition, the full-lines are arranged from an upper or lower edge of the image to the opposite edge to reproduce the arrangement of the pixels representative of the body or object scanned.
In addition to the sorting and reassociation functions performed on interlaced half-lines of image data, it is sometimes desirable to produce scanned image data having different matrix dimensions (i.e., rows of pixels by columns of pixels), depending upon the type of feature being imaged and the detail desired. Accordingly, circuitry employed for processing and sorting half-lines of pixel data would advantageously accommodate the variety of matrix formats envisioned.
In an exemplary embodiment, the invention provides an approach to sorting partial or half-lines of image data produced by an imaging detector. The half-lines of data are received by processing circuitry and are assigned memory storage addresses. The memory storage addresses for each half-line of data are determined by a half-line counter with reference to a base address table. Values corresponding to output locations are stored in the base address table. The values are changed by reference to offsets. As the half-line counter is incremented for sequentially received half-lines of data, the memory addresses in which the data are stored are determined uniquely, by reference to the base address table and offsets. The resulting sequence of storage addresses orders the half-lines of data to associate the data into sequential full-lines for reconstitution of the scanned image.
The technique facilitates the use of various scan modes and matrix sizes. By altering the base addresses and offsets used to generate the output memory address locations, various scanning modes may be employed, including outside-to-inside scanning and inside-to-outside scanning. Moreover, by setting the proper values in the base address table and by using appropriate offsets, a variety of pixel matrix dimensions may be accommodated by the same system, in a computationally efficient manner.